Large forage bales of hay or silage have gained tremendous popularity in agriculture during the past decade. This is due to the storage requirements for the bales as well as the lower power requirements found in baling the forage as compared to chopping it. At moisture levels of 61%, round baling of forage requires 2.3 kW per hour/metric ton (h/t) of Dry Matter (DM) and chopping the forage requires 7.22 kW h/t DM. At moisture levels of 15%, the energy needed for baling is only 1.1 kW h/t DM. Therefore, large hay or silage bales are an attractive alternative for farmers due to the lower energy requirement to harvest the forage.
One of the preferred manners of feeding cows is to give them a Total Mixed Ration (TMR) of feed prepared with a mixer. A TMR of feed is defined as being everything a cow eats in one single mixture. It has been reported that over half of the cows in the United States are fed using the TMR feed. This is largely due to the TMR feed providing uniform nutritional value in every mouthful. Consequently, the TMR feed allows for better monitoring of feed intake and provides a feed with improved digestibility. The problem presented by the large forage bales is that they are not readily usable in TMR mixing systems. In order to introduce the baled forage into a TMR mixer, some processing must be done to the bale. This processing includes the reduction of the bale and reduction of the forage particles contained in the bale.
Currently, there are bale reduction machines available to process the large bales in a form useable by TMR mixers, however, most of them require a great deal of power in the range of 45 and 60 kW. These power requirements generally necessitate the use of a large power unit such as a tractor. Current bale reduction machines also excessively reduce the particle size of the forage. Ideally a large forage bale processor should reduce particle size of the forage just enough to facilitate mixing and delivery in the TMR mixer and no more. Studies have indicated that when particle size is decreased excessively, milk fat percentage and digestion efficiency can decrease. Finely chopped feed may also cause improper rumen function and a decrease in rumen pH. It has been suggested that 19 mm is the critical length of forage particles and that particle sizes lower than this fail to stimulate rumination. So, it appears that while particle reduction is necessary for handling purposes, any additional particle size reduction is not beneficial for animal nutrition.
There are several tub grinders available that process large hay bales into a form useable by most TMR mixers. Most of these grinders use a grinding or shredding motion to process the hay. These grinders require large amounts of power which are on the order of 26 kW h/t DM. Another design uses a slicing motion, but this has not been adapted to process large round bales. In addition, bale grinders also create substantial losses of forage during the processing. The grinding losses have been measured to be between two and nine percent, with the potential for much higher loss in extreme windy conditions when the grinder is used outside. Most of these losses are from the leaves, which are the most fragile and nutritious parts of the forage. Also available is a large bale shredder which requires less power than the previously mentioned tub grinders. The shredder utilizes three rotating cylinders with knives attached to the perimeter. The cylinders rotated at about 210 rpm and the processing (feed) rate was approximately 0.75 kg/s which is, or about one-seventh the rate of tub grinders. The average length of cut was about 50 mm and it required 4.05 kW h/t DM to process the bales. Although the design reduced the power requirements, it still produced an excessive amount of dust, making it unacceptable for use in closed buildings.
It is the objective of this invention to provide a large forage bale processor which slices large forage bales into material suitable for use in most TMR mixers, reduces the energy consumed during processing and controls the particle size reduction of the baled forage.